In a pot, over medium heat, add the apples, sugar and cinnamon.
Cook on medium/low heat for about 15 minutes until the apples have softened significantly, but without burning the sugar.
Add the apple mixture to a powerful blender with the melted butter (be sure that your blender can handle hot contents).
Blend until you reach a smooth, buttery consistency.
Let cool fully (this will allow it to thicken and form a spreadable butter consistency). Spoon the mixture into an air-tight container or jar and keep refrigerated.
Notes
*This apple butter will last up to two weeks in an airtight container, stored in the fridge.